So I was battling Starpower at Ubers just now, and my Palkia used Aura Sphere on her Darkrai. I was aggravated to see that Darkrai lived with 2% HP (which cost me the match, I might add), and even more so when I ran the damage calculations post-battle.

According to the calcs, it would be physically impossible for Darkrai to live, the only other conditions were Rain, which wouldn't make a difference. Light Screen was not up, so don't suggest that, and I am absolutely sure that is what happened. So the question is, how?